In general, a seat belt for protecting a passenger is installed in a vehicle, and the seat belt includes seat belt webbing extending from a fixing portion mounted at a lower side portion of a vehicle seat, passing through a webbing guide, and being wound by a retractor with a predetermined force.
A tongue of the seat belt is mounted at one end of the seat belt webbing extending between the fixing portion and the webbing guide, and multiple sections of the seat belt webbing extending between the webbing guide and the retractor are slidably inserted in a vertical direction into a guide holder mounted at an inner side of the vehicle.
Also, a buckle to be coupled to the tongue is connected to the fixing portion mounted in the lower side portion of the seat.